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Abstract

Examples of cast grates whose construction was based on previously used "old" patterns of the technological equipment for heat treatment furnaces (TEq) are presented. Manufacturers of this type of castings have at their disposal numerous earlier designs of the applied TEq. Their adaptation for the needs of a new order, i.e. the creation of a new design or modification of the already existing one, significantly reduces both cost and time of the implementation. It also allows making new grate constructions of various shapes and sizes, reducing in this way the number of patterns stored by the manufacturer of castings. The examples of cast grates shown and discussed in this study document the variety of ways that can be used when making them from the already existing patterns or castings. The presented grates were made using master patterns, entire castings or their fragments, and modular segments.

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Authors and Affiliations

B. Piekarski
A. Drotlew
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Abstract

The article deals with the gas development of the geopolymer binder system hardened by heat and provides the comparison with organic binder systems. The GEOPOL® W technology is completely inorganic binder system, based on water. This fact allow that the gas generated during pouring is based on water vapour only. No dangerous emissions, fumes or unpleasant odours are developed. The calculated amount of water vapour generated from GEOPOL® W sand mixture is 1.9 cm3/g. The measured volume of gas for GEOPOL® W is 4.3 cm3/g. The measurement of gas evolution proves that the inorganic binder system GEOPOL® W generates very low volume of gas (water vapour) in comparison with PUR cold box amine and Croning. The amount of gas is several times lower than PUR cold box amine (3.7x) and Croning (4.2x). The experiment results are consistent with the literature sources. The difference between the calculated and the measured gas volume is justified by the reverse moisture absorption from the air after dehydration during storing and preparing the sand samples. Minimal generated volumes of gas/water vapour brings, mainly as was stated no dangerous emissions, also the following advantages: minimal risk of bubble defects creation, the good castings without defects, reduced costs for exhaust air treatment, no condensates on dies, reduced costs for cleaning.

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Authors and Affiliations

M. Vykoukal
A. Burian
M. Přerovská
T. Bajer
J. Beňo
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Abstract

This article presents the preparation of composite casts made using the technology of precise casting by the method of melted models. The composite was reinforced with the ceramic sinter from Al2O3 particle shaped in a printed polystyrene female mould, which was fired together with precured ceramics. The resulting ceramic preform, after being saturated with paraffin and after the filling system is installed, was filled with liquid moulding sand and fired together with the mould. The reinforcement was saturated by means of the counter-pressure exerting action on the metal column, being a resultant of pressures inside and outside the chamber. The preliminary assessment showed no apparent defects in the shape of the cast. The casting was measured and the figures were compared with the dimensions of the matrix in which the reinforcing preform was made, the preform after firing and after saturation with paraffin. The results were presented in a table and dimensional deviations were determined. The composite casting was subjected to metallographic tests, which excluded any porous defects or damage to the reinforcement. It can therefore be said that, according to the predictions resulting from the previous calculations, the pressure values used allowed for complete filling of the reinforcement capillaries. The proposed method is therefore suitable for the preparation of precision composite castings with complex shapes.

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Authors and Affiliations

P. Szymański
K. Gawdzińska
D. Nagolska

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